1. Field of the Invention
The present invention relates to the production of tablets of sodium dichloroisocyanurate, and more particularly to the production of tablets having flame resistance and thermal stability sufficient to avoid chain reaction thermal decomposition.
Sodium dichloroisocyanurate is a widely used solid chlorine compound which is effective to release active chlorine for various purposes such as for sterilizing water in swimming pools and sewerage.
2. Description of the Prior Art
For storing, transportation and use, it is preferable to supply sodium dichloroisocyanurate in tablet form.
Production of sodium dichloroisocyanurate in tablet form is disclosed in Japanese Pat. No. 513,484 (Jap. Pat. Publn. No. 23 198/1967) granted to the assignee of the present patent application. In the referenced patent, sodium dichloroisocyanurate powder is kneaded with sufficient water to produce a predetermined water content in the resulting kneaded material. The kneaded material is compressed into tablets using a surface pressure of about 1,000 Kg/cm.sup.3. U.S. Pat. No. 3,956,444 to William H. Kibbel, Jr. discloses sodium dichloroisocyanurate dihydrate tablets produced by a surface pressure of from about 2,000 to about 10,000 p.s.i.
The method disclosed in the Japanese patent has the disadvantage that wet dichloroisocyanurate is sticky. The stickiness adversely affects continuously supplying fixed amounts of the material to a tabletting machine. Therefore, this method is not suitable for use on an industrial scale.
The method of the United States patent has the advantage that tablets of sodium dichloroisocyanurate dihydrate produced thereby have flame resistance to avoid chain reaction thermal decomposition, but it has the disadvantage that, due to a water content of 14.1 weight %, it is sticky. The stickiness causes the same operational difficulty as in the Japanese patent. There is also the possibility that water may be released with a slight increase in heat in the tablet. Since the temperature at which the dihydrate is converted to the monohydrate lies at about 66.7.degree. C., the resulting tablet products may be thus converted during storage and/or transportation and may cause agglomeration due to adhesion thereof.